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Wednesday, June 27, 2012

JEE 2013: On Percentile Ranking

Unfortunately, he has once again missed an important point. ISI report talks about two primary assumptions. They are:

Aggregate scores are expected to increase from less meritorious to more meritorious students in any particular subject.

Merit distribution is the same in all boards.

Now, Prof. Barua, raises this issue of what is merit, and very cleverly uses different definitions of merit for justifying the two assumptions. For the first assumption, he says, "marks are not given randomly. The student who does better, gets more
marks. Clearly, if this is questioned, Board marks cannot be used for
anything." For the second assumption, he says, "I cannot do much more but to suggest synonyms
for merit in this context: innate ability, intelligence."

What do marks represent. Do they represent innate ability or do they represent academic preparation. I have never seen any teacher or any board or any educationist ever claiming that marks in the board exam represent (even in statistical sense) innate ability. They are supposed to represent academic preparation (san corruption, cheating, copying, etc.). Just try giving the 12th class board exam paper to a 5 year old, who is brilliant in everything s/he does, and you are not likely to get 100 out of 100.

So, if the definition of merit is "innate ability" then assumption 2 may be correct (as he says, there is no way to prove it, but let me give it to him). But no educationist will ever agree that whatever that undefined entity called "innate intelligence" is, that has a linear relationship with board marks, not just in total, but individually in each subject. Prof. Barua wants us to believe that someone with higher "innate intelligence" is likely to score higher marks (in statistical sense) in every subject, irrespective of the subject.

On the other hand, if the definition of merit is "academic preparation" (and this is the only logical definition that can be used when we talk about board marks in various subjects), then I have already shown in an earlier blog and many others have pointed out other studies that merit distribution is not same across all boards, and in particular, ICSE and CBSE have higher concentration of academically well prepared students. And hence the assumption 2 behind percentile based normalization does not hold.

Hence, simple percentile ranking is not good. It is unfair to students of higher quality boards.

He then says that if the board performance across 42 boards have to be compared, then percentile ranking is the best. I can challenge that too, but there is an "if" in his statement. I think he needs to answer first, why board performance needs to be compared at all. Isn't there any other method to encourage students to go back to schools.

Percentile ranking is the easiest to explain to masses, and in particular to bureaucrats, politicians, and administrators (like IIT Directors). So, if you are taking a political decision, then percentile ranking is the best. But if you are taking an academic decision, there are ways to study the performance of boards, and hence give higher and lower weight to boards. It should be possible to say that 90 percentile student of a good quality board has a similar level of academic preparation as a 95 percentile of a poorer quality board (for a hypothetical case).